Navigation Links
Tiny nanocubes help scientists tell left from right
Date:6/28/2013

UPTON, NY-In chemical reactions, left and right can make a big difference. A "left-handed" molecule of a particular chemical composition could be an effective drug, while its mirror-image "right-handed" counterpart could be completely inactive. That's because, in biology, "left" and "right" molecular designs are crucial: Living organisms are made only from left-handed amino acids. So telling the two apart is important-but difficult.

Now, a team of scientists at the U.S. Department of Energy's Brookhaven National Laboratory and Ohio University has developed a new, simpler way to discern molecular handedness, known as chirality. They used gold-and-silver cubic nanoparticles to amplify the difference in left- and right-handed molecules' response to a particular kind of light. The study, described in the journal Nano Letters, provides the basis for a new way to probe the effects of handedness in molecular interactions with unprecedented sensitivity.

"Our discovery and methods based on this research could be extremely useful for the characterization of biomolecular interactions with drugs, probing protein folding, and in other applications where stereometric properties are important," said Oleg Gang, a researcher at Brookhaven's Center for Functional Nanomaterials and lead author on the paper. "We could use this same approach to monitor conformational changes in biomolecules under varying environmental conditions, such as temperature-and also to fabricate nano-objects that exhibit a chiral response to light, which could then be used as new kinds of nanoscale sensors."

The scientists knew that left- and right-handed chiral molecules would interact differently with "circularly polarized" light-where the direction of the electrical field rotates around the axis of the beam. This idea is similar to the way polarized sunglasses filter out reflected glare unlike ordinary lenses.

Other scientists have detected this difference, called "circular dichroism," in organic molecules' spectroscopic "fingerprints"-detailed maps of the wavelengths of light absorbed or reflected by the sample. But for most chiral biomolecules and many organic molecules, this "CD" signal is in the ultraviolet range of the electromagnetic spectrum, and the signal is often weak. The tests thus require significant amounts of material at impractically high concentrations.

The team was encouraged they might find a way to enhance the signal by recent experiments showing that coupling certain molecules with metallic nanoparticles could greatly increase their response to light (see: http://www.bnl.gov/newsroom/news.php?a=11157). Theoretical work even suggested that these so-called plasmonic particles-which induce a collective oscillation of the material's conductive electrons, leading to stronger absorption of a particular wavelength-could bump the signal into the visible light portion of the spectroscopic fingerprint, where it would be easier to measure.

The group experimented with different shapes and compositions of nanoparticles, and found that cubes with a gold center surrounded by a silver shell are not only able to show a chiral optical signal in the near-visible range, but even more striking, were effective signal amplifiers. For their test biomolecule, they used synthetic strands of DNA-a molecule they were familiar with using as "glue" for sticking nanoparticles together.

When DNA was attached to the silver-coated nanocubes, the signal was approximately 100 times stronger than it was for free DNA in the solution. That is, the cubic nanoparticles allowed the scientists to detect the optical signal from the chiral molecules (making them "visible") at 100 times lower concentrations.

"This is a very large optical amplification relative to what was previously observed," said Fang Lu, the first author on the paper.

The observed amplification of the circular dichroism signal is a consequence of the interaction between the plasmonic particles and the "exciton," or energy absorbing, electrons within the DNA-nanocube complex, the scientists explained.

"This research could serve as a promising platform for ultrasensitive sensing of chiral molecules and their transformations in synthetic, biomedical, and pharmaceutical applications," Lu said.

"In addition," said Gang, "our approach offers a way to fabricate, via self-assembly, discrete plasmonic nano-objects with a chiral optical response from structurally non-chiral nano-components. These chiral plasmonic objects could greatly enhance the design of metamaterials and nano-optics for applications in energy harvesting and optical telecommunications."


'/>"/>

Contact: Karen McNulty Walsh
kmcnulty@bnl.gov
631-344-8350
DOE/Brookhaven National Laboratory
Source:Eurekalert

Related biology news :

1. Self-assembling nanocubes for next generation antennas and lenses
2. Stanford scientists develop gene therapy approach to grow blood vessels in ischemic limbs
3. Queens scientists seek vaccine for Pseudomonas infection
4. Scientists produce eye structures from human blood-derived stem cells
5. American Society of Plant Biologists honors early career women scientists
6. Brandeis scientists win prestigious prize for circadian rhythms research
7. Scientists discover new method of proton transfer
8. Salk scientists open new window into how cancers override cellular growth controls
9. WileyChina.com - Now Featuring Bespoke Pages for China’s Life Scientists
10. Scientists win $2 million to study new pathway in development and maintenance of lymphoma
11. UGA scientists reveal genetic mutation depicted in van Goghs sunflower paintings
Post Your Comments:
*Name:
*Comment:
*Email:
(Date:1/11/2017)... 11, 2017 Intoxalock, a leading ignition interlock ... of its patent-pending calibration device. With this new technology, ... securely upload data logs and process repairs at service ... "Fighting drunk driving through the application of cutting-edge ... large, but also for the customer who can get ...
(Date:1/6/2017)...  Delta ID Inc., a leader in consumer-grade iris ... at CES® 2017. Delta ID has collaborated with Gentex ... use of iris scanning as a secure, reliable and ... a car, and as a way to elevate the ... Delta ID and Gentex will demonstrate (booth #7326 LVCC) ...
(Date:12/22/2016)... , Dec. 20, 2016  As part of its longstanding ... leading personal genetics company, recently released its latest children,s book, ... The book focuses on the topics of inheritance and variation ... Standards (NGSS) taught in elementary school classrooms in the US. ... series by illustrator Ariana Killoran , whose previous book ...
Breaking Biology News(10 mins):
(Date:1/23/2017)... ... 2017 , ... AxioMed will be presenting its viscoelastic cervical ... Montego Bay, Jamaica from January 26-28th. “We’re excited to be presenting the benefits ... the simplicity of the surgical technique,” said Jake Lubinski, President of AxioMed. ...
(Date:1/21/2017)... ... 20, 2017 , ... G&L Scientific Inc, a leading provider ... ), has announced the opening of new offices in Cambridge, Massachusetts, strengthening and ... This is the latest step in G&L’s expansion of its global clinical consulting ...
(Date:1/21/2017)... CA (PRWEB) , ... January 21, 2017 , ... ... our ongoing endeavors to bring to market a pioneering medical device for the ... has signed an engagement contract with Emergo, a global regulatory consultancy that helps ...
(Date:1/21/2017)... BOULDER, Colo. , Jan. 20, 2017 ... ("Bioptix" or the "Company"), announced that on January 14, ... a plan under which the Company will terminate certain ... subsidiary, Bioptix Diagnostics, Inc.  The Company commenced terminations on ... completed within 30 days.  The Company may pay severance ...
Breaking Biology Technology: